Why Is There a Custom to Eat Kreplach on Purim

Kreplach, dumplings, which are made of meat wrapped in dough and then cooked or fried, are traditionally eaten on Purim, Hashanah Rabbah, and erev Yom Kippur. On these three days there are no restrictions of work as there on Yom Tov. Nevertheless, there exists an element of Yom Tov on each of these days because we sit down to festive meals.

We eat meat on Yom Tov because the Torah commands, ושמחת בחגך – “You shall rejoice on your festival” (Devorim 16:14), and Chazal explain, אין שמחה אלא בבשר – “There is no rejoicing without meat” (Pesochim 109a). Since Purim, Hoshanah Rabbah, and erev Yom Kippur are partial or “covered” Yomim Tovim, we eat foods that contain meat, but are “covered”. (Otzar Taamei HaMinhagim pg. 456)